SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 68: Poster: Oxide and Insulator Surfaces
O 68.3: Poster
Mittwoch, 29. März 2023, 18:00–20:00, P2/EG
Vanadium and iron intermixing in honeycomb oxides on Pt(111) and Ru(0001) — •Piotr Wemhoff1, Claudine Noguera2, Jacek Goniakowski2, and Niklas Nilius1 — 1Carl von Ossietzky University, Institute of Physics, D-26111 Oldenburg, Germany — 2CNRS-Sorbonne University, UMR 7588, INSP, F-75005 Paris, France
Whereas V and Fe are immiscible in bulk-type perovskite oxides, mixed oxide honeycomb layers can be prepared on Pt(111) and Ru(0001) surfaces. Their atomic composition is accessible from bias-dependent STM topographic images, as the Fe ions develop a protruding contrast with respect to V when tunneling into their 3d(z2) orbitals at elevated bias. On Pt(111), up to 50% iron can be incorporated into a V2O3 host oxide, whereby the Fe runs through a series of distinct configurations evolving from isolated ions to pairs in 3rd neighbor positions, short chains of 2nd neighbor Fe and finally ordered (2x2) V/Fe islands separated by domain boundaries. The observed phase behavior can be traced back to attractive Fe-V and repulsive Fe-Fe pair interactions, which have been identified by DFT calculations and enable perfect reproduction of the experimental patterns by means of Monte-Carlo simulations. In contrast, a V/Fe self-organization scheme becomes active on Ru(0001) that only allows for one unique cation arrangement in the honeycomb oxide. DFT finds a layer of interfacial oxygen between Ru(0001) and the oxide film to be responsible for this rigid structural composition.